The Occupational Studies Section conducts epidemiologic studies to determine the role factors from the workplace play in the origin of cancer. Major areas of focus include pesticides, organic solvents and other widely used chemicals, and organic and inorganic dusts. Projects are underway to clarify the provocative associations between pesticides and certain cancers found in earlier Section studies. Cohort mortality studies of pesticide applicators employed by a national lawn care company and county noxious weed departments have recently been initiated. Results from a case-control study of lymphatic and hematopoietic cancer in Nebraska will be available shortly. Nasopharyngeal cancer was found to be associated with occupational exposure to formaldehyde in a case-control study, resembling findings from a mortality study of industrial workers. A study of embalmers is underway which includes a detailed industrial hygiene monitoring component for formaldehyde and other chemicals to clarify cancer excesses reported in this occupation. The 10-fold excess of astrocytic brain cancer associated with long-term employment in the electronics industry in a case-control study appeared to be more closely related to solvent and other chemical exposures than to electromagnetic radiation. Evaluation of the risk of bladder cancer among persons employed in the chemical industry using data from the National Bladder Cancer Survey found few significant excesses, although men employed for more than 20 years in the production of organic chemicals had a 2.4-fold excess. Major efforts underway include industrial workers exposed to acrylonitrile; grain millers exposed to fumigants; workers in dusty trades exposed to silica; workers in China exposed to benzene; firefighters exposed to combustion products; and furniture workers exposed to wood dusts, metal fumes, and paints, varnishes and solvents. Methodologic studies are being conducted to improve exposure assessment procedures and to develop resources for occupational studies such as a referent data base composed of workers.